wow, a sensible reply without any name calling and no cheap shots, didn't think it was possible so deserves sensible comment
to an extent I agree with the dead rubber scenario and it was probabaly one of our lowest of low lights, we were crap
one thing that I noticed watching the Windies back then is that they were the most competitive and ruthless team I had ever seen, they would go absolutely apeshit celebrating the last wicket as if it were the first, it was also very difficult to get into that team, sooooo much depth, their second string attack would have also rolled us in a day and half
the lead up into the last test at the SCG was huge and the media really played up on the fact that the pitch would be a turner and it was a viscous turner, watching the windies bat on it they were like a fish out of water, wickets fell trying to hit us out of the park rather than playing cricket shots
we had a plan that worked and despite the windies, in articular Clive Lloyd saying spin was not an issue for them they looked all at sea.
I believe the pitch and our playing 2 spinners would have provided us with the same result if it were the first test as our plan seem to work pretty well
as for why they didn't have the same problem in the subcontinent, I have no explanation but they certainly had problems with our crappy spin attack on those 2 tours in the early to mid 80s
without checking the results, from memory they did not have to chase too many runs in the subcontinent as their bowlers performed on those pitches and they were not as doctored as the recent pitches when India played RSA.